pureErrorAnova: Pure Error analysis of variance

Description

For a linear model object, finds the sum of squares for lack of fit
and the sum of squares for pure error. These are added to the standard anova table
to give a test for lack of fit. If there is no pure error, then the regular anova
table is returned.

Usage

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### This is a generic function. pureErrorAnova(mod)## S3 method for class 'lm'pureErrorAnova(mod)### Methods for other than models for type lm have not been defined.

Arguments

mod

an object of type lm

Details

For regression models with one predictor, say y ~ x, this method fits
y ~ x + factor(x) and prints the anova table. With more than one predictor, it
computes a random linear combination L of the terms in the mean function
and then gives the anova table for update(mod, ~.+factor(L)).